Albumen

Albumen is the only binder in this encyclopaedia whose preparation begins by damaging it on purpose. Fresh egg white is the wrong material: it is stringy, unevenly viscous and alkaline, and it will not lie down flat on a sheet of paper. What albumen printing wants is egg white that has been beaten, salted, acidified and then left alone for a week — and, in the industry that eventually supplied most of the world, deliberately fermented for several days more.

In photography

It made the standard photographic print of the nineteenth century. The Getty’s atlas and the AIC’s conservation wiki agree on the dates: Louis Désiré Blanquart-Evrard described the process to the French Academy of Sciences on 27 May 1850; by 1855 albumen was the dominant photographic printing process, and it stayed dominant to the end of the century. Nothing else in this course was ever that widely used.

It is a salted paper with a better surface. The AIC’s process description is short: the paper is sized and salted, sensitised with silver nitrate by brushing or floating, dried, printed out by contact under a negative in ultraviolet light, then rinsed, toned, fixed and washed. The Getty adds the salting step’s chemistry — a solution of sodium chloride or ammonium chloride is added to the egg white before coating — so the chloride is inside the binder, and the silver chloride forms in the albumen layer rather than in the paper fibre. That is the whole difference from a salted paper, and it is why the image sits on the surface: the AIC’s identification note gives the image layer as photolytic silver on an albumen binder, colloidal rather than filamentary.

The gloss was the point, and it was unpopular. The Getty records that early albumen prints, before about 1870, were usually less glossy than the later double-coated and burnished ones, and that in the 1850s “the glossiness of albumen photographs was highly criticised in the photographic literature”, because the public was accustomed to the matte character of salt prints. Taste changed; double coating and burnishing pushed the gloss further; and the argument about surface that every alternative printer still has with themselves started here.

It has three other jobs, all structural. Reilly records fermented albumen in use by the mid-1850s as a substratum on glass to improve the adhesion of collodion. The AIC’s collodion page lists it among the aqueous pre-coats — with gum arabic, dextrin and gelatin — applied before varnishing a collodion negative, so the alcohol in the varnish cannot reach the binder. And Ware’s list of the additives put into salted papers as protecting agents includes egg white alongside milk, isinglass, rice water, honey, gum arabic and sugar candy.

⚗Three denaturing treatments, and why none of them is optional

Reilly’s account of preparing albumen is a short course in protein chemistry disguised as a workshop note, and it explains every step of a procedure that otherwise looks like superstition.

Beating. The proteins in egg white have different viscosities, so native albumen is not one substance but several behaving differently. Beating it to a froth and letting it settle back to a liquid denatures them and produces a homogeneous liquid that will form an even layer.

Chloride. The salt is there to make silver chloride when the sheet is sensitised — but Reilly notes that the chlorides also help to denature the albumen, and that one visible effect of adding them is to reduce the volume of froth produced during beating.

Acid. The third treatment is adjustment of pH downwards, with acid or with alcohol. Reilly gives the reason in one line: the chemical forces which bind together the enormous protein molecules grow weaker as the pH is lowered, and the physical properties change as a result. Native egg white is alkaline at pH 7.8; glossy papers are made with partially decomposed, acidic albumen, which coats more evenly, gives a glossier surface and has less tendency to yellow after sensitisation. Fresh alkaline albumen is used only for matte papers, and then always mixed with starch or another substance.

Taken together the effect is, in Reilly’s words, to change the egg white completely and irreversibly. There is no undoing it and no reconstituting the original.

Properties

A viscous liquid, alkaline at pH 7.8 when fresh and acidic once prepared, coagulating irreversibly with heat, drying to a thin transparent film that takes a high gloss. No formula, no molar mass, no melting point.

Its most distinctive property is that ageing improves it up to a point and then ruins it. Reilly describes a prepared albumen after settling and a week in a refrigerator as a yellowish homogeneous liquid with a slight aged odour that signals its readiness. The nineteenth-century industry pushed much further: some albumenisers let the material ferment at elevated temperatures for several days, using naturally occurring bacteria, and Reilly records that the fermented albumen gave glossier paper that toned better. The Dresden factories, which from the early 1870s supplied most of the world’s albumen paper, made fermentation standard — and, he adds, Dresden paper could readily be identified by the smell.

The material’s third property only shows up over a century. The AIC lists three proposed causes of the highlight yellowing that is now almost universal in surviving albumen prints: image silver bonding to sulfur-containing side groups of the albumen protein to form silver sulfide, which is yellow; a Maillard reaction, in which glucose in the albumen combines with amino groups of the egg protein to give a highly coloured insoluble compound, accelerated by high humidity and alkaline conditions; and the oxidation of benzene-ring amino acids on absorbing light. The binder is attacking its own image, by more than one route, using material that was in the egg.

Handling

There is no GHS classification and no exposure limit, and the front matter above says what was searched and what EH40’s own caveat is. The controls that matter here are not toxicological. They are the ordinary controls for keeping a protein liquid that is wanted partly decomposed: a covered vessel, refrigeration, dated labels, and the judgement to throw a batch away. The course has read no published assessment of the microbiological side of deliberate fermentation and does not offer one.

Why Level A. Against the course rubric, albumen as a material meets Level A on every criterion: no classification approaching the ceiling of irritant, harmful if swallowed or corrosive; no heating; no mains-voltage work; and waste that is dilute rinse water.

⚠The one operation that takes this out of Level A

Sensitising it with silver nitrate. The rubric names silver nitrate explicitly among the Level B criteria, and an albumenised sheet becomes photographic only when it is floated on or brushed with a silver nitrate solution. From that point the assessment belongs to silver nitrate — corrosive, staining, and a substance whose spills are permanent — and to the ultraviolet exposure that follows, which brings its own Level B controls.

The distinction is worth keeping sharp because albumen printing is one of the processes this course does teach, in Part XXIII. Nothing about the binder makes it difficult. Everything that raises the level of an albumen printing session arrives afterwards, from another bottle.

Waste

Dilute albumen in rinse water is organic load. Everything else in the tray belongs to something else: the first rinse off a sensitised sheet carries silver and goes with the silver stream; the fixing bath goes to recovery; a gold or other toning bath carries its metal. Bottle each stream separately and label it, as ILFORD instructs domestic users to do. Check your local regulations; they govern.

History

The albumen print is the nineteenth century’s mass medium, and the industry behind it was an agricultural one. Dresden became its centre because it sat close to the sources of raw paper stock and enjoyed an abundant supply of low-cost eggs — and, Reilly notes, lower labour costs than its English or American competitors. The paper itself had to be extraordinary: thin, smooth and of exceptionally high quality, free of the metal flecks that came from buttons left in the rags and from the paper-making machinery, and made with mineral-free water, which in the 1850s only nature could supply. The mill at Rives in France drew its water from a mountain lake fed by melting alpine snow.

The permanence problem arrived almost immediately. The AIC records that albumen print deterioration was referenced as early as 1855, when the Photographic Society of London set up its Fading Committee, and that the causes it reported were imperfect washing, an old or insufficiently acidic hypo bath, acidity in the mounting materials, and excessive moisture and sulfur in the atmosphere. Its recommendation was thorough washing and toning with gold chloride. That is a nineteenth-century committee arriving, from failures in the field, at the two controls this course still teaches — wash properly and tone with gold — and it did so within five years of the process being published.